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                BJOI2015 回家的路                </h1>
                <p>时间限制：10s&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;  空间限制：256MB</p>			</div>
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                                <h3>题目描述</h3><p><div>
<div>小强和阿米巴是好朋友。连接北京和小强的家乡的是错综复杂的铁路网。一共有N个站点，站点之间有长短不一的</div>
<div>双向的铁路。小强每次回家的时候，会从所有的最短路中随机选择一条。阿米巴门前有一条铁路。他想在不改变北</div>
<div>京到小强的家乡的最短路的距离的前提下，给这个铁路网再添一条长度为K的单向 单向铁路，使得小强路过阿米巴</div>
<div>家门口的那条铁路的概率最大。请输出这个最大概率。</div>
</div>
<p></p></p><hr/><h3>输入格式</h3><p><div>
<div>第一行是三个正整数N,M和K，表示站点的数量，铁路线的数量和新开的铁路线的长度。站点从1编号到N。北京是1</div>
<div>号点，小强的家乡是N号。接下来M行，每行三个正整数u,v,s表示有一条连接站点u和v的铁路线长度是s。这M行中</div>
<div>的第一行描述的是阿米巴家门口的铁路。两个点之间可能有多条铁路。也有可能u=v，即，有自环。你新修建的铁</div>
<div>路也可以和已有线路重合，也可以是自环。1和N之间一定是连通的。</div>
<div>3&le;N&le;100000，M&le;400000，1&le;s,K&le;10000,保证无论如何加边图中任两点之间的最短路的数量都不超过2^16000.</div>
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<div></div>
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<p></p></p><hr/><h3>输出格式</h3><p><div>
<div>输出一行两个正整数A,B，表示从A向B修建一条单向铁路。你的修建方案得出的小强路过的概率和标准答案之间的</div>
<div>差距不超过10-6即可算对。</div>
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<p></p></p><hr/><h3>样例输入</h3><pre>3 3 1
1 2 1
2 3 1
1 3 2</pre><hr/><h3>样例输出</h3><pre>2 3
//添加边之后，一共有3条最短路，小强会路过阿米巴门前的概率由1/2变为2/3.</pre><hr/><h3>提示</h3><p><div>尚无Spj，请谨慎提交!</div>
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<p></p></p><hr/><h3>题目来源</h3><p>没有写明来源</p>
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